A coated type magnetic recording medium has been widely used which is prepared by dispersing magnetic particles (e.g., .gamma.-Fe.sub.2 O.sub.3, Co-doped .gamma.-Fe.sub.2 O.sub.3, Fe.sub.3 O.sub.4, Co-doped Fe.sub.3 O.sub.4, Bertholide compound of .gamma.-Fe.sub.2 O.sub.3 and .gamma.-Fe.sub.3 O.sub.4, magnetic oxide particles such as CrO.sub.2, magnetic alloy particles mainly composed of ferromagnetic particles such as Co or Ni) in an organic binder such as a vinyl chloride-vinyl acetate copolymer, a styrene-butadiene copolymer, an epoxy resin or a polyurethane resin, coating the composition on a non-magnetic support, and drying.
With the recent increase in the amount of information to be recorded, a magnetic recording medium suitable for high density recording must be manufactured. Various research and studies have been developed to manufacture a thin film type magnetic recording medium which is prepared by forming a ferromagnetic thin film on a non-magnetic support by vacuum evaporation, sputtering, ion plating or plating without using a binder which is used for preparing a coated type magnetic recording medium.
The vacuum deposition method for preparing a magnetic recording medium by vaporizing magnetic metal in a vacuum atmosphere and coating it on a non-magnetic support to form a thin film is practically very useful because the steps and appratuses for preparing the film are relatively simple.
However, a metal thin film type magnetic recording medium has poor anti-corrosion properties and poor lubricity. Many attempts have been made to remove the above defects but satisfactory solutions have not been obtained. For example, there are a method of incorporating a metal such as Cr to improve anti-corrosion property of a magnetic recording layer itself, a method of conducting vapor deposition of magnetic metal in an oxygen atmosphere to incorporate oxygen, and further over-coating metal such as Al or Cr metal oxide thereof to provide anti-corrosion properties and lubricity and still further providing high molecular materials and lubricants by vapor deposition, coating and plasma polymerization. However, none of those have been found to be satisfactory.